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This paper describes our custom-designed wireless gait analysis sensor (WGAS) system developed and tested for real-time fall detection. The WGAS is capable of differentiating falls vs. Activities of Daily Living (ADL) and the Dynamic Gait Index (DGI) performed by young volunteers using a Back Propagation Artificial Neural Network (BP ANN) algorithm. The WGAS, which includes a tri-axial accelerometer, 2 gyroscopes, and a MSP430 microcontroller is worn by the subjects at either T4 (at back) or the belt-clip positions (in front of the waist) for the various falls, ADL, and Dynamic Gait Index (DGI) tests. The raw data is wirelessly transmitted from the WGAS to a nearby PC for real-time fall classification, where six features were extracted for the BP ANN. Overall fall classification accuracies of 97.0% and 97.4% have been achieved for the data taken at the T4 and at the belt position, respectively. The preliminary data demonstrates an overall sensitivity of 97.0% and overall specificity of 97.2% for this WGAS fall detection system, showing good promise as a real-time low-cost and effective fall detection device for wireless acute care and wireless assisted living.

The inherent tendency of lectins to agglutinate cells has limited their use as reagents for the detection of carbohydrate groups on cell surfaces by flow cytometry. In the current study, we demonstrate a method for the use of a fluoresceinated tetrameric isolectin (Griffonia simplicifolia I-A3B, FITC-GS I-A3B) as a functionally monovalent, nonagglutinating probe in flow cytometry. This isolectin contains three A subunits and one B subunit. Both types of subunits bind alpha-D-galactopyranosyl (alpha-D-galp-) end groups with similar affinities; however, the A subunits have a 1,000-fold greater affinity for N-Acetyl-D-galactosamine (GalNAc) than does the B subunit. The addition of low (1-2 mM) concentrations of GalNAc to the FITC-GS I-A3B isolectin results in blockage of the three A subunits without significantly affecting the B subunit; this yields a functionally monovalent probe for the detection of cell surface alpha-D-Galp end groups. This approach has been used to examine two types of cells: Ehrlich ascites tumor cells and rat alveolar macrophages, both of which are known to express cell surface alpha-D-Galp end groups. Lectin binding, as determined by number of positive cells and fluorescence intensity, was dependent upon concentration of the lectin and haptenic sugar. Specificity of the staining was demonstrated by the ability of methyl alpha-D-galactopyranoside (Met alpha-D-Galp) to abolish the binding of the lectin to the cells. Elimination of both GalNAc and Met alpha-D-Galp from the staining solution resulted in agglutination of the cells, indicating that the A subunits were active in the absence of GalNAc.